This makes a great “ocean” (water) background for painted paper collages (make fishes out of painted paper).  It is super easy and  I do have some very helpful hints to make it a sure fire success.  I video taped the process of making a bubble print – for visual learners like myself (if I see it, I can do it!).
What you will need:
liquid dish soap
paper (heavy paper like cardstock or watercolor paper – Tip: construction paper does not work well)
plastic straws
a straight pin

Fill your basin with water.  Any size basin will work – it just needs to be bigger than the size of your paper.  Add a very healthy amount of dish soap.  Think of it this way – the soap bubbles carry the color pigment.  I probably add about a 1/4 cup or more (depending on the size of the basin).   Next add a healthy amount of paint.  I add about a cup of paint or better (keep adding paint if your prints are not showing the bubbles).  This is a very “intensely-soapy-pigmented” water!!!  But it works like magic!  (note – not all paints are equal in their vibrancy.  Play around with it to achieve the look you want.  I like to add a little cheap acrylic paint to my tempera to up its depth.)
There is no other way to mix the batch without putting your hand in the basin.  The pigment of the paint falls to the bottom and you really need to get your hand in there to stir it up into the bubbles.  You will see the bubbles change into a deeper color as you stir with your hand.   (Do this regularly as you print to keep it vibrant – I also use a paint brush to stir but you will need an occasional hand stir.)

Give the student a straw to blow bubbles into the water (tell them to “blow out”).  Once there is a dense covering of bubbles, lay your paper on top of the bubbles.  Let the weight of the paper pop the bubbles.  Do not push the paper down!  This will dip it into the water and ruin the bubble prints.  Pull it out before it hits the water.
TIP:  Poke a hole in the straw to help keep students from sucking up the soapy water.

Watch the printing process:

Bubble Print Making from Fairy Dust Teaching on Vimeo.